The present invention generally relates to apparatus for extruding thermoplastic filaments and, more particularly, apparatus for spunbonding multi-component filaments.
Spunbonding or other techniques for extruding fine diameter filaments find many different applications in various industries including, for example, in nonwoven material manufacturing. This technology generally involves extruding a thermoplastic material from multiple rows of discharge outlets extending along the lower surface of an elongate spinneret. Spunbonded materials are used in such products as diapers, surgical gowns, carpet backings, filters and many other consumer and industrial products.
The machines for spunbonding such materials can be very large with the filament discharge outlets numbering in the thousands.
For certain applications, it is desirable to utilize multiple types of thermoplastic liquid materials to form individual cross-sectional portions of each filament. Often, these multi-component filaments comprise two components and, therefore, are referred to as bicomponent filaments. For example, when manufacturing nonwoven materials for use in the garment industry, it may be desirable to produce bicomponent filaments having a sheath-core construction. The sheath may be formed from a softer material which is comfortable to the skin of an individual and the core may be formed from a stronger, but perhaps less comfortable material having greater tensile strength to provide durability to the garment. Another important consideration involves cost of the material. For example, a core of inexpensive material may be combined with a sheath of more expensive material. For example, the core may be formed from polypropylene or nylon and the sheath may be formed from a polyester or co-polyester. Many other multi-component fiber configurations exist, including side-by-side, tipped, and microdenier configurations, each having its own special applications. Various material properties can be controlled using one or more of the component liquids. These include, as examples, thermal, chemical, electrical, optical, fragrance, and anti-microbial properties. Likewise, many types of die tips exist for combining the multiple liquid components just prior to discharge or extrusion to produce filaments of the desired cross-sectional configuration.
One problem associated with multi-component extrusion apparatus involves the cost and complexity of the manifolds used to transmit each of the separate component liquids to the multi-component die tip. Typical manifolds must be machined with many different passages leading to the die tip to ensure that the proper flow of each component liquid reaches the die tip under the proper pressure and temperature conditions. These manifolds are therefore relatively complex and expensive components of the multi-component extrusion apparatus.
For these reasons, it would be desirable to provide multicomponent extrusion apparatus having a manifold system which may be easily manufactured and yet fulfils the requirement of effectively transmitting each of the component liquids to the multi-component die tip.
The present invention therefore provides an apparatus for extruding multiple types of liquid materials into multi-component filaments including a unique manifold structure coupled with a multi-component die tip. Generally, the invention pertains to melt spinning apparatus, such as spunbonding and meltblowing apparatus. The preferred or illustrative embodiment specifically disclosed herein relates to a spunbonding apparatus. In one general aspect, the apparatus comprises an intermediate manifold element having first and second opposite surfaces. First and second outer manifold elements respectively couple to the first and second opposite surfaces and have respective opposed surfaces. Each opposed surface respectively abuts one of the first and second opposite surfaces of the intermediate manifold element. A first channel is formed between the opposed surface of the first outer manifold element and the first opposite surface of the intermediate manifold element. A second channel is formed between the opposed surface of the second outer manifold element and the second opposite surface of the intermediate manifold element. The first and second channels have inlets for respectively receiving the first and second liquids and outlets for respectively discharging the first and second liquids. These inlets and outlets may be formed in the intermediate manifold element, in the outer manifold elements, or between the intermediate manifold element and the respective outer manifold elements. The first and second channels may comprise recesses formed in the first and second opposite surfaces of the intermediate manifold element, or recesses formed in the opposed surfaces of the first and second outer manifold elements, or any combination thereof which forms the necessary channels.
A die tip is coupled adjacent the manifold elements. The die tip includes a plurality of multi-component filaments discharge outlets and at least first and second liquid distribution passages. The first and second liquid distribution passages are adapted to receive the first and second liquids respectively from the outlets of the first and second channels. A liquid combining member communicates between the first and second liquid distribution passages and the filament discharge outlets. The liquid combining member is configured to receive the first and second liquids and combine the first and second liquids into respective multi-component filaments.
In a more specific preferred embodiment of the manifold structure, the first and second outer manifold elements have respective recesses and, more preferably, a plurality of recesses on their respective opposed surface. The intermediate manifold element is coupled between the respective opposed surfaces of the first and second outer manifold elements. The recesses on the respective first and second opposite surfaces of the intermediate manifold element communicate, and preferably align with corresponding recesses on the opposed surfaces of the first and second outer manifold elements. The communicating recesses together form at least first and second channels and, preferably, first and second pluralities of channels each having a liquid inlet and a liquid outlet communicating with the die tip on the opposite sides of the intermediate manifold element.
Various advantages, objectives, and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.